As a countermeasure against static electricity, to spray air ion to an electrically-charged body as an object required to be electrically neutralized and to electrically neutralize the object, an ion generating apparatus which is also referred to as “ionizer” or “charge neutralization apparatus” is used. In a manufacturing line for manufacturing and assembling electronic components, the ion generating apparatus is used for removing static electricity from the electronic components, manufacturing and assembling jigs and the like as the object. By spraying air ion to the object, foreign substances can be prevented from being adhered to the electronic components and the like by the static electricity, and the electronic components can be prevented from being broken or adhered to the jigs by the static electricity.
The ion generating apparatus used for a purpose such as this ionizes air by applying an alternating voltage between a discharge electrode and an opposite electrode and generating corona discharge around the discharge electrode with compressed air being supplied to the discharge electrode from outside. By an alternating corona discharge method in which an alternating voltage is applied between those electrodes, positive and negative ions are alternatively and periodically generated.
A positive/negative air ion measuring apparatus configured to measure the amount of positive ions and the amount of negative ions at the same time is described in Patent Document 1, and a charge neutralization apparatus configured to measure the amount of ions in ionized air is described in Patent Document 2.